This invention relates to rigging slings, and specifically to a sling with means for spreading or separating a pair of sling cables when used with one lifting hook.
Devices currently in use for separating or spreading lifting slings typically use a rigid bar fastened between the sling cables to separate them. However, use of a rigid bar presents many problems. While a long separator bar tends to reduce the chances of entanglement of the sling cables, it becomes very cumbersome when a worker attempts to use such a device since it is harder to control. On the other hand, when the bar is made shorter to increase the ease of operating the rig, the chances of the slings getting twisted or entangled around each other increases. Furthermore, a solid separator bar is not adaptable to various lifting requirements in terms of the distance between the points at which the lifting slings are attached to the load.
Conventional devices which do not adequately separate the sling cables also present the situation of workers having to stretch and reach for the hook while untangling the slings. This presents hazards and safety problems in that a worker could stumble in attempting to untangle the slings. Moreover, heavy loads are often involved and therfore the use of heavy hooks is required presenting a danger that the heavy hook or headache ball may strike and injure a worker attempting to free twisted lifting cables.
Various devices for lifting which feature a method of separating the slings are illustrated in the patent to Natoli, U.S. Pat. No. 2,573,216, and the patent to Smith, U.S. Pat. No. 1,573,878. The Natoli device for hoisting and lowering barrels, etc., utilizes two lifting cables having a spring secured at the lower ends of the lifting chains for bringing the ends together. The Smith patent shows a structure with rigid links and arms, with the arms connected by a cable which serves as a release member.
Other difficulties encountered with past devices for separating slings include lost production time associated with worker labor involved in untangling idle cables, as well as longer hook-up times. Furthermore, conventional separators are usually of significant weight, making rigging operations mor laborious and hazardous.
It is therefore an object of the present invention to construct a sling separator which serves to keep a pair of lifting cables from becoming tangled when hanging idle from one lifting hook. It is another object of the present invention to provide a rigging sling whcih permits a rigger to work at a greater distance from the hook or headache ball, and thus increase the working radius of the hook.
It is a further object of the present invention to construct a sling separator which overcomes any adverse reactions the wire rope slings may exhibit when put under stress of weight. Specifically, it is an object that the invention permit the sling to rotate freely when put under stress of a load. It is an object of the present invention to permit a variable distance of separation between the slings, and to allow the slings to swing freely to form an angle anywhere from approximately 0.degree. to 180.degree.. It is an object of the present invention to provide a sling separator which is flexible and movable to meet the many situations associated with rigging, while presenting only a slight increase of weight in the rigging hardware.
It is an object of the present invention to provide a faster hook-up and release time for the riggers, and to enable the riggers to work from a safe and comfortable position while completing their rigging assignment. Another object is to provide a device which allows for decreased time for each hook-up.
Another object of the present invention is to provide some additional footage of spread (length) down to the lower (working) slings, e.g.; slings fitted to cradle a box; slings fitted to reach the ends of a piece of pipe; slings to choke a bundle of pipe. This added footage of length delivered by the sling of the present invention will thus utilize shorter working slings representing an added cost savings in purchasing new slings.